Eukaryotic Cell Structure Organelles

Eukaryotic Cell Structure Eukaryotic cells contain many structures that act as specialized organs known as organelles Eukaryotic cells are classified into two major parts: 1) the nucleus, and 2) the cytoplasm – the portion of the cell outside of the nucleus

Nucleus is the control center of the cell contains the genetic material known as DNA (deoxyribonucleic acid)  DNA provides the instructions for making proteins and other important molecules contains chromatin - consists of DNA bound to protein → condenses to form chromosomes

Ribosomes Proteins are assembled (synthesized) on the ribosomes  produce proteins by following coded instructions that come from the nucleus * Cells that synthesize a lot of proteins are filled with ribosomes Analogy: a machine in a factory / construction workers

Endoplasmic Reticulum (ER) internal membrane system of the cell site where lipid components of the cell membrane are assembled, as well as proteins and other materials that are exported from the cell Analogy: an assembly line

Endoplasmic Reticulum cont. Rough ER – involved in the synthesis and modification of proteins → lined with ribosomes Smooth ER – contain enzymes that synthesize membrane lipids

Golgi Apparatus modifies, sorts, and packages proteins and other materials from the ER for storage in the cell or secretion outside of the cell Analogy: customization shop / postal service

Lysosomes filled with enzymes → proteins involved in chemical reactions digest, or breakdown, lipids, carbohydrates, proteins, and even organelles that have outlived their usefulness (they remove junk) Analogy: recycling center

Vacuoles saclike structures that store materials, such as: water, salts, proteins, and carbohydrates Analogy: Storage Garage

Vacuoles cont. in plants, there is often a large central vacuole filled with fluid  the pressure of the central vacuole makes it possible for plant cells to support heavy structures such as leaves and flowers Vacuoles are also found in some unicellular and animal cells  a contractile vacuole pumps excess water out of the cell important for homeostasis

Mitochondria and Chloroplasts All living things require a source of energy  most cells get energy in one of two ways: from food molecules or from the sun * Both organelles contain their own genetic information

Mitochondria convert chemical energy stored in food into compounds that are more convenient for the cells to use enclosed by two membranes Analogy: Coal-Burning Power Plant

Chloroplasts contained in plant cells and some other organisms capture energy from the sunlight and convert it into chemical energy through a process called photosynthesis enclosed by two membranes Analogy: Solar Powered Cells

Cytoskeleton supporting structure and transportation system of the cell  gives cells their shape and internal organization microfilaments and microtubules make up a cells cytoskeleton centrioles → important in cell division